Mindless words can betray whether you're romantically interested in your date — and scientists built a computer program to find them

No way! I use a lot of function words, too!
Reuters/Eddie Keogh
Imagine that you're on a first date.

Over a couple of drinks, you cover the usual suspects: favorite foods, dream jobs, where you each grew up.

On the way home, you wonder: Were they into me? They were smiling a lot, so probably. But they also looked at their watch a few times, so probably not.

How frustrating.

Now imagine that the whole time you two were talking, scientists were sitting under the table transcribing the conversation. (It's creepy, but bear with me.)

By the end of the night, those scientists could tell you pretty quickly how likely it is that your date wants to see you again.

It's not magic — it's Linguistic Inquiry and Word Count (LIWC).

LIWC is a computer program that scientists, including the psychologist James Pennebaker, created in the early 1990s. According to the LIWC website, the program sifts through text looking for patterns that reflect different emotions, thinking styles, and social concerns.

The 40 conversations that the researchers analyzed took place during a study on speed dating among heterosexual men and women. Participants went on four-minute dates that researchers recorded.

After the dates, participants filled out surveys about how much they had in common with their partner and, of course, whether they would be interested in seeing their partners again.

Results showed that partners who'd used similar "function words" — connector words such as "the," "this," and "I" — were more interested in seeing each other again.

And that's not because we're attracted to people who are similar to us — the researchers observed this phenomenon even among partners who were pretty different. Rather, the researchers say that when we're romantically interested in someone, we shift our language to match theirs.

What's more, a second study found that heterosexual couples who used similar function words in their IM conversations were more likely to still be together three months later.

Unfortunately, Pennebaker told NPR that, as far as he knows, people can't pick up on patterns in function word use — we need LIWC's help. So don't waste your time scrutinizing your date's use of the word "the."